In material processing methodologies, pattern etching comprises the application of a thin layer of a light-sensitive material, such as a photo-resist, to an upper surface of a substrate that is subsequently patterned in order to provide a mask for transferring this pattern to the underlying thin film during etching. The patterning of the light-sensitive material generally includes exposing the light-sensitive material to a radiation source through a reticle (and associated optics) using, for example, a photo-lithography sensitive system, and removing the irradiated regions of the light-sensitive material (as in the case of a positive photo-resist) or non-irradiated regions (as in the case of negative photo-resist) using a developing solvent. Moreover, this mask layer may comprise multiple sub-layers. Photo-lithographic methods are limited dimensionally by the wavelengths of light or electromagnetic radiation used to react with the photo-resist, and the corresponding optics required to manage the wavelengths of light.
More recently, double patterning technologies have been used to meet the increasing need to produce smaller features. There are two dominant methods for double patterning: (1) sidewall or spacer processes and (2) double lithography processes. In the spacer process, the spacer is used as the final mask to create the final pattern in the thin film. The spacer is generated in a multi-layer mask, wherein the mask layer may comprise a light-sensitive material, such as the photo-resist described above.
However, conventional methods have not yielded the desired high-profile features. There is thus a need for new methods for forming ultra-thin raised features on substrates and/or ultra-thin features formed in substrates.